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Splash Documentation
Release 1.5
Scrapinghub
March 04, 2015Contents
1 Documentation 3
1.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Splash HTTP API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Splash Scripts Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.4 Splash Scripts Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
1.5 Splash and IPython (Jupyter) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
1.6 Splash Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
1.7 Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
iii
Splash Documentation, Release 1.5
Splash is a javascript rendering service. It’s a lightweight web browser with an HTTP API, implemented in Python us-
ing Twisted and QT. The (twisted) QT reactor is used to make the sever fully asynchronous allowing to take advantage
of webkit concurrency via QT main loop. Some of Splash features:
• process multiple webpages in parallel;
• get HTML results and/or take screenshots;
• turn OFF images or use Adblock Plus rules to make rendering faster;
• execute custom JavaScript in page context;
• transparently plug into existing software using Proxy interface;
• get detailed rendering info in HAR format.
Contents 1Splash Documentation, Release 1.5 2 Contents
CHAPTER 1
Documentation
1.1 Installation
1.1.1 Linux + Docker
1. Install Docker.
2. Pull the image:
$ sudo docker pull scrapinghub/splash
3. Start the container:
$ sudo docker run -p 5023:5023 -p 8050:8050 -p 8051:8051 scrapinghub/splash
4. Splash is now available at 0.0.0.0 at ports 8050 (http), 8051 (https) and 5023 (telnet).
1.1.2 OS X + Docker
1. Install Docker (via Boot2Docker).
2. Pull the image:
$ docker pull scrapinghub/splash
3. Start the container:
$ docker run -p 5023:5023 -p 8050:8050 -p 8051:8051 scrapinghub/splash
4. Figure out the ip address of boot2docker:
$ boot2docker ip
The VM’s Host only interface IP address is: 192.168.59.103
5. Splash is available at the returned IP address at ports 8050 (http), 8051 (https) and 5023 (telnet).
1.1.3 Ubuntu 12.04 (manual way)
1. Install system dependencies:
3Splash Documentation, Release 1.5
$ sudo add-apt-repository -y ppa:pi-rho/security
$ sudo apt-get update
$ sudo apt-get install libre2-dev
$ sudo apt-get install netbase ca-certificates python \
python-dev build-essential libicu48 \
xvfb libqt4-webkit python-twisted python-qt4
2. TODO: install Python dependencies using pip, clone repo, chdir to it, start splash.
To run the server execute the following command:
python -m splash.server
Run python -m splash.server --help to see options available.
By default, Splash API endpoints listen to port 8050 on all available IPv4 addresses. To change the port use --port
option:
python -m splash.server --port=5000
Requirements
# install PyQt4 (Splash is tested on PyQT 4.9.x and PyQT 4.11.x)
# and the following packages:
twisted
qt4reactor
psutil
adblockparser >= 0.2
-e git+https://github.com/axiak/pyre2.git#egg=re2
xvfbwrapper
Pillow
# for scripting support
lupa >= 1.1
funcparserlib >= 0.3.6
# the following libraries are only required by tests
pytest
pyOpenSSL
requests >= 1.0
jsonschema >= 2.0
strict-rfc3339
1.1.4 Splash Versions
docker pull scrapinghub/splash will give you the latest stable Splash release. To obtain the latest devel-
opment version use docker pull scrapinghub/splash:master. Specific Splash versions are also avail-
able, e.g. docker pull scrapinghub/splash:1.2.1.
1.1.5 Customizing Dockerized Splash
Passing Custom Options
To run Splash with custom options pass them to docker run. For example, let’s increase log verbosity:
4 Chapter 1. DocumentationSplash Documentation, Release 1.5
$ docker run -p 8050:8050 scrapinghub/splash -v3
To see all possible options pass --help. Not all options will work the same inside Docker: changing ports doesn’t
make sense (use docker run options instead), and paths are paths in the container.
Folders Sharing
To set custom Request Filters use -v Docker option. First, create a folder with request filters on your local filesystem,
then make it available to the container:
$ docker run -p 8050:8050 -v :/etc/splash/filters scrapinghub/splash
Replace with a path of your local folder with request filters.
Docker Data Volume Containers can also be used. Check https://docs.docker.com/userguide/dockervolumes/ for more
info.
Proxy Profiles and Javascript Profiles can be added in a similar way:
$ docker run -p 8050:8050 \
-v :/etc/splash/proxy-profiles \
-v :/etc/splash/js-profiles \
scrapinghub/splash
To setup Custom Lua Modules mount a folder to /etc/splash/lua_modules. If you use a Lua sandbox (default)
don’t forget to list safe modules using --lua-sandbox-allowed-modules option:
$ docker run -p 8050:8050 \
-v :/etc/splash/lua_modules \
--lua-sandbox-allowed-modules ’module1;module2’ \
scrapinghub/splash
Warning: Folder sharing (-v option) doesn’t work on OS X and Windows (see
https://github.com/docker/docker/issues/4023). It should be fixed in future Docker & Boot2Docker releases. For
now use one of the workarounds mentioned in issue comments or clone Splash repo and customize its Dockerfile.
Splash in Production
In production you may want to daemonize Splash, start it on boot and restart on failures. Since Docker 1.2 an easy
way to do this is to use --restart and -d options together; another way to do that is to use standard tools like
upstart, systemd or supervisor.
Note: --restart option won’t work without -d.
Please also take into account the memory usage: Splash uses an unbound in-memory cache and so it will eventually
consume all RAM. A workaround is to restart the process when it uses too much memory; there is Splash --maxrss
option for that. You can also add Docker --memory option to the mix.
In production it is a good idea to pin Splash version - instead of scrapinghub/splash it is usually better to use
something like scrapinghub/splash:1.4.
The final command for starting a long-running Splash server which uses up to 4GB RAM and daemonizes & restarts
itself could look like this:
1.1. Installation 5Splash Documentation, Release 1.5
$ docker run -d -p 8050:8050 --memory=4.5G --restart=always scrapinghub/splash:1.4 --maxrss 4000
1.2 Splash HTTP API
Consult with Installation to get Splash up and running.
Splash is controlled via HTTP API. For all endpoints below parameters may be sent either as GET arguments or
encoded to JSON and POSTed with Content-Type: application/json header.
The most versatile endpoint that provides all Splash features is execute (WARNING: it is still experimental). Other
endpoints may be easier to use in specific cases - for example, render.png returns a screenshot in PNG format that can
be used as img src without any further processing, and render.json is convenient if you don’t need to interact with a
page.
The following endpoints are supported:
1.2.1 render.html
Return the HTML of the javascript-rendered page.
Arguments:
url [string][required] The url to render (required)
baseurl [string][optional] The base url to render the page with.
If given, base HTML content will be feched from the URL given in the url argument, and render using this as
the base url.
timeout [float][optional] A timeout (in seconds) for the render (defaults to 30).
By default, maximum allowed value for the timeout is 60 seconds. To override it start Splash with
--max-timeout command line option. For example, here Splash is configured to allow timeouts up to 2
minutes:
$ python -m splash.server --max-timeout 120
wait [float][optional] Time (in seconds) to wait for updates after page is loaded (defaults to 0). Increase this value if
you expect pages to contain setInterval/setTimeout javascript calls, because with wait=0 callbacks of setInter-
val/setTimeout won’t be executed. Non-zero wait is also required for PNG rendering when doing full-page
rendering (see render_all).
proxy [string][optional] Proxy profile name. See Proxy Profiles.
js [string][optional] Javascript profile name. See Javascript Profiles.
js_source [string][optional] JavaScript code to be executed in page context. See Executing custom Javascript code
within page context.
filters [string][optional] Comma-separated list of request filter names. See Request Filters
allowed_domains [string][optional] Comma-separated list of allowed domain names. If present, Splash won’t load
anything neither from domains not in this list nor from subdomains of domains not in this list.
viewport [string][optional] View width and height (in pixels) of the browser viewport to render the web page. Format
is “x”, e.g. 800x600. Default value is 1024x768.
‘viewport’ parameter is more important for PNG rendering; it is supported for all rendering endpoints because
javascript code execution can depend on viewport size.
6 Chapter 1. DocumentationSplash Documentation, Release 1.5
For backward compatibility reasons, it also accepts ‘full’ as value; viewport=full is semantically equivalent
to render_all=1 (see render_all).
images [integer][optional] Whether to download images. Possible values are 1 (download images) and 0 (don’t
downoad images). Default is 1.
Note that cached images may be displayed even if this parameter is 0. You can also use Request Filters to strip
unwanted contents based on URL.
headers [JSON array or object][optional] HTTP headers to set for the first outgoing request.
This option is only supported for application/json POST requests. Value could be either a JSON array
with (header_name, header_value) pairs or a JSON object with header names as keys and header
values as values.
“User-Agent” header is special: is is used for all outgoing requests, unlike other headers.
Examples
Curl example:
curl ’http://localhost:8050/render.html?url=http://domain.com/page-with-javascript.html&timeout=10&wa
The result is always encoded to utf-8. Always decode HTML data returned by render.html endpoint from utf-8 even if
there are tags like
in the result.
1.2.2 render.png
Return a image (in PNG format) of the javascript-rendered page.
Arguments:
Same as render.html plus the following ones:
width [integer][optional] Resize the rendered image to the given width (in pixels) keeping the aspect ratio.
height [integer][optional] Crop the renderd image to the given height (in pixels). Often used in conjunction with the
width argument to generate fixed-size thumbnails.
render_all [int][optional] Possible values are 1 and 0. When render_all=1, extend the viewport to include the
whole webpage (possibly very tall) before rendering. Default is render_all=0.
Note: render_all=1 requires non-zero wait parameter. This is an unfortunate restriction, but it seems that
this is the only way to make rendering work reliably with render_all=1.
scale_method [string][optional] Possible values are raster (default) and vector. If scale_method=raster,
rescaling operation performed via width parameter is pixel-wise. If scale_method=vector, rescaling is
done element-wise during rendering.
Note: Vector-based rescaling is more performant and results in crisper fonts and sharper element boundaries,
however there may be rendering issues, so use it with caution.
1.2. Splash HTTP API 7Splash Documentation, Release 1.5
Examples
Curl examples:
# render with timeout
curl ’http://localhost:8050/render.png?url=http://domain.com/page-with-javascript.html&timeout=10’
# 320x240 thumbnail
curl ’http://localhost:8050/render.png?url=http://domain.com/page-with-javascript.html&width=320&heig
1.2.3 render.har
Return information about Splash interaction with a website in HAR format. It includes information about requests
made, responses received, timings, headers, etc.
You can use online HAR viewer to visualize information returned from this endpoint; it will be very similar to “Net-
work” tabs in Firefox and Chrome developer tools.
Currently this endpoint doesn’t expose raw request and response contents; only meta-information like headers and
timings is available.
Arguments for this endpoint are the same as for render.html.
1.2.4 render.json
Return a json-encoded dictionary with information about javascript-rendered webpage. It can include HTML, PNG
and other information, based on arguments passed.
Arguments:
Same as render.png plus the following ones:
html [integer][optional] Whether to include HTML in output. Possible values are 1 (include) and 0 (exclude). Default
is 0.
png [integer][optional] Whether to include PNG in output. Possible values are 1 (include) and 0 (exclude). Default
is 0.
iframes [integer][optional] Whether to include information about child frames in output. Possible values are 1 (in-
clude) and 0 (exclude). Default is 0.
script [integer][optional] Whether to include the result of the executed javascript final statement in output (see Exe-
cuting custom Javascript code within page context). Possible values are 1 (include) and 0 (exclude). Default is
0.
console [integer][optional] Whether to include the executed javascript console messages in output. Possible values
are 1 (include) and 0 (exclude). Default is 0.
history [integer][optional] Whether to include the history of requests/responses for webpage main frame. Possible
values are 1 (include) and 0 (exclude). Default is 0.
Use it to get HTTP status codes and headers. Only information about “main” requests/responses is returned (i.e.
information about related resources like images and AJAX queries is not returned). To get information about all
requests and responses use ‘har’ argument.
har [integer][optional] Whether to include HAR in output. Possible values are 1 (include) and 0 (exclude). Default
is 0. If this option is ON the result will contain the same data as render.har provides under ‘har’ key.
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Examples
By default, URL, requested URL, page title and frame geometry is returned:
{
"url": "http://crawlera.com/",
"geometry": [0, 0, 640, 480],
"requestedUrl": "http://crawlera.com/",
"title": "Crawlera"
}
Add ‘html=1’ to request to add HTML to the result:
{
"url": "http://crawlera.com/",
"geometry": [0, 0, 640, 480],
"requestedUrl": "http://crawlera.com/",
"html": "-->",
"requestedUrl": "http://www.youtube.com/embed/lSJvVqDLOOs?version=3&rel=1&fs=1&showsearch
"childFrames": []
}
],
"requestedUrl": "http://scrapinghub.com/autoscraping.html"
}
Note that iframes can be nested.
Pass both ‘html=1’ and ‘iframes=1’ to get HTML for all iframes as well as for the main page:
{
"geometry": [0, 0, 640, 480],
"frameName": "",
1.2. Splash HTTP API 9Splash Documentation, Release 1.5
"html": "",
"requestedUrl": "http://www.youtube.com/embed/lSJvVqDLOOs?version=3&rel=1&fs=1&showsearch
"childFrames": []
}
],
"requestedUrl": "http://scrapinghub.com/autoscraping.html"
}
Unlike ‘html=1’, ‘png=1’ does not affect data in childFrames.
When executing JavaScript code (see Executing custom Javascript code within page context) add the parameter
‘script=1’ to the request to include the code output in the result:
{
"url": "http://crawlera.com/",
"geometry": [0, 0, 640, 480],
"requestedUrl": "http://crawlera.com/",
"title": "Crawlera",
"script": "result of script..."
}
The JavaScript code supports the console.log() function to log messages. Add ‘console=1’ to the request to include
the console output in the result:
{
"url": "http://crawlera.com/",
"geometry": [0, 0, 640, 480],
"requestedUrl": "http://crawlera.com/",
"title": "Crawlera",
"script": "result of script...",
"console": ["first log message", "second log message", ...]
}
Curl examples:
# full information
curl ’http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&png=1&html=1&ifr
# HTML and meta information of page itself and all its iframes
curl ’http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&html=1&iframes=1
# only meta information (like page/iframes titles and urls)
curl ’http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&iframes=1’
# render html and 320x240 thumbnail at once; do not return info about iframes
curl ’http://localhost:8050/render.json?url=http://domain.com/page-with-iframes.html&html=1&png=1&wid
# Render page and execute simple Javascript function, display the js output
curl -X POST -H ’content-type: application/javascript’ \
-d ’function getAd(x){ return x; } getAd("abc");’ \
10 Chapter 1. DocumentationSplash Documentation, Release 1.5
’http://localhost:8050/render.json?url=http://domain.com&script=1’
# Render page and execute simple Javascript function, display the js output and the console output
curl -X POST -H ’content-type: application/javascript’ \
-d ’function getAd(x){ return x; }; console.log("some log"); console.log("another log"); getAd("a
’http://localhost:8050/render.json?url=http://domain.com&script=1&console=1’
1.2.5 execute
Warning: This endpoint is experimental. API could change in future releases.
Execute a custom rendering script and return a result.
render.html, render.png, render.har and render.json endpoints cover many common use cases, but sometimes they are
not enough. This endpoint allows to write custom Splash Scripts.
Arguments:
lua_source [string][required] Browser automation script. See Splash Scripts Tutorial for more info.
timeout [float][optional] Same as ‘timeout’ argument for render.html.
allowed_domains [string][optional] Same as ‘allowed_domains’ argument for render.html.
proxy [string][optional] Same as ‘proxy’ argument for render.html.
filters [string][optional] Same as ‘filters’ argument for render.html.
1.2.6 Executing custom Javascript code within page context
Note: See also: executing JavaScript in Splash scripts
Splash supports executing JavaScript code within the context of the page. The JavaScript code is executed after the
page finished loading (including any delay defined by ‘wait’) but before the page is rendered. This allow to use the
javascript code to modify the page being rendered.
To execute JavaScript code use js_source parameter. It should contain JavaScript code to be executed.
Note that browsers and proxies limit the amount of data can be sent using GET, so it is a good idea to use
content-type: application/json POST request.
Curl example:
# Render page and modify its title dynamically
curl -X POST -H ’content-type: application/json’ \
-d ’{"js_source": "document.title=\"My Title\";", "url": "http://example.com"}’ \
’http://localhost:8050/render.html’
Another way to do it is to use a POST request with the content-type set to ‘application/javascript’. The body of the
request should contain the code to be executed.
Curl example:
# Render page and modify its title dynamically
curl -X POST -H ’content-type: application/javascript’ \
-d ’document.title="My Title";’ \
’http://localhost:8050/render.html?url=http://domain.com’
1.2. Splash HTTP API 11Splash Documentation, Release 1.5
To get the result of a javascript function executed within page context use render.json endpoint with script = 1 param-
eter.
In Splash-as-a-proxy mode use X-Splash-js-source header instead of a POST request.
Javascript Profiles
Splash supports “javascript profiles” that allows to preload javascript files. Javascript files defined in a profile are
executed after the page is loaded and before any javascript code defined in the request.
The preloaded files can be used in the user’s POST’ed code.
To enable javascript profiles support, run splash server with the --js-profiles-path= option:
python -m splash.server --js-profiles-path=/etc/splash/js-profiles
Note: See also: Splash Versions.
Then create a directory with the name of the profile and place inside it the javascript files to load (note they must be
utf-8 encoded). The files are loaded in the order they appear in the filesystem. Directory example:
/etc/splash/js-profiles/
mywebsite/
lib1.js
To apply this javascript profile add the parameter js=mywebsite to the request:
curl -X POST -H ’content-type: application/javascript’ \
-d ’myfunc("Hello");’ \
’http://localhost:8050/render.html?js=mywebsite&url=http://domain.com’
Note that this example assumes that myfunc is a javascript function defined in lib1.js.
Javascript Security
If Splash is started with --js-cross-domain-access option
python -m splash.server --js-cross-domain-access
then javascript code is allowed to access the content of iframes loaded from a security origin diferent to the original
page (browsers usually disallow that). This feature is useful for scraping, e.g. to extract the html of a iframe page. An
example of its usage:
curl -X POST -H ’content-type: application/javascript’ \
-d ’function getContents(){ var f = document.getElementById("external"); return f.contentDocument
’http://localhost:8050/render.html?url=http://domain.com’
The javascript function ‘getContents’ will look for a iframe with the id ‘external’ and extract its html contents.
Note that allowing cross origin javascript calls is a potential security issue, since it is possible that secret information
(i.e cookies) is exposed when this support is enabled; also, some websites don’t load when cross-domain security is
disabled, so this feature is OFF by default.
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1.2.7 Request Filters
Splash supports filtering requests based on Adblock Plus rules. You can use filters from EasyList to remove ads and
tracking codes (and thus speedup page loading), and/or write filters manually to block some of the requests (e.g. to
prevent rendering of images, mp3 files, custom fonts, etc.)
To activate request filtering support start splash with --filters-path option:
python -m splash.server --filters-path=/etc/splash/filters
Note: See also: Splash Versions.
The folder --filters-path points to should contain .txt files with filter rules in Adblock Plus format. You may
download easylist.txt from EasyList and put it there, or create .txt files with your own rules.
For example, let’s create a filter that will prevent custom fonts in ttf and woff formats from loading (due to qt bugs
they may cause splash to segfault on Mac OS X):
! put this to a /etc/splash/filters/nofonts.txt file
! comments start with an exclamation mark
.ttf|
.woff|
To use this filter in a request add filters=nofonts parameter to the query:
curl ’http://localhost:8050/render.png?url=http://domain.com/page-with-fonts.html&filters=nofonts’
You can apply several filters; separate them by comma:
curl ’http://localhost:8050/render.png?url=http://domain.com/page-with-fonts.html&filters=nofonts,eas
If default.txt file is present in --filters-path folder it is used by default when filters argument is not
specified. Pass filters=none if you don’t want default filters to be applied.
To learn about Adblock Plus filter syntax check these links:
• https://adblockplus.org/en/filter-cheatsheet
• https://adblockplus.org/en/filters
Splash doesn’t support full Adblock Plus filters syntax, there are some limitations:
• element hiding rules are not supported; filters can prevent network request from happening, but they can’t hide
parts of an already loaded page;
• only domain option is supported.
Unsupported rules are silently discarded.
Note: If you want to stop downloading images check ‘images’ parameter. It doesn’t require URL-based filters to
work, and it can filter images that are hard to detect using URL-based patterns.
Warning: It is very important to have pyre2 library installed if you are going to use filters with a large number of
rules (this is the case for files downloaded from EasyList).
Without pyre2 library splash (via adblockparser) relies on re module from stdlib, and it can be 1000x+ times slower
than re2 - it may be faster to download files than to discard them if you have a large number of rules and don’t use
re2. With re2 matching becomes very fast.
Make sure you are not using re2==0.2.20 installed from PyPI (it is broken); use the latest version from github.
1.2. Splash HTTP API 13Splash Documentation, Release 1.5
1.2.8 Proxy Profiles
Splash supports “proxy profiles” that allows to set proxy handling rules per-request using proxy parameter.
To enable proxy profiles support, run splash server with --proxy-profiles-path= option:
python -m splash.server --proxy-profiles-path=/etc/splash/proxy-profiles
Note: If you run Splash using Docker, check Folders Sharing.
Then create an INI file with “proxy profile” config inside the specified folder, e.g.
/etc/splash/proxy-profiles/mywebsite.ini. Example contents of this file:
[proxy]
; required
host=proxy.crawlera.com
port=8010
; optional, default is no auth
username=username
password=password
[rules]
; optional, default ".*"
whitelist=
.*mywebsite\.com.*
; optional, default is no blacklist
blacklist=
.*\.js.*
.*\.css.*
.*\.png
whitelist and blacklist are newline-separated lists of regexes. If URL matches one of whitelist patterns and matches
none of blacklist patterns, proxy specified in [proxy] section is used; no proxy is used otherwise.
Then, to apply proxy rules according to this profile, add proxy=mywebsite parameter to request:
curl ’http://localhost:8050/render.html?url=http://mywebsite.com/page-with-javascript.html&proxy=mywe
If default.ini profile is present, it will be used when proxy argument is not specified. If you have
default.ini profile but don’t want to apply it pass none as proxy value.
1.2.9 Splash as a Proxy
Splash supports working as HTTP proxy. In this mode all the HTTP requests received will be proxied and the response
will be rendered based in the following HTTP headers:
X-Splash-render [string][required] The render mode to use, valid modes are: html, png and json. These modes have
the same behavior as the endpoints: render.html, render.png and render.json respectively.
X-Splash-js-source [string] Allow to execute custom javascript code in page context. See Executing custom
Javascript code within page context.
X-Splash-js [string] Same as ‘js’ argument for render.html. See Javascript Profiles.
X-Splash-timeout [string] Same as ‘timeout’ argument for render.html.
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X-Splash-wait [string] Same as ‘wait’ argument for render.html.
X-Splash-proxy [string] Same as ‘proxy’ argument for render.html.
X-Splash-filters [string] Same as ‘filters’ argument for render.html.
X-Splash-allowed-domains [string] Same as ‘allowed_domains’ argument for render.html.
X-Splash-viewport [string] Same as ‘viewport’ argument for render.html.
X-Splash-images [string] Same as ‘images’ argument for render.html.
X-Splash-width [string] Same as ‘width’ argument for render.png.
X-Splash-height [string] Same as ‘height’ argument for render.png.
X-Splash-render-all [string] Same as ‘render_all’ argument for render.png.
X-Splash-scale-method [string] Same as ‘scale_method’ argument for render.png.
X-Splash-html [string] Same as ‘html’ argument for render.json.
X-Splash-png [string] Same as ‘png’ argument for render.json.
X-Splash-iframes [string] Same as ‘iframes’ argument for render.json.
X-Splash-script [string] Same as ‘script’ argument for render.json.
X-Splash-console [string] Same as ‘console’ argument for render.json.
X-Splash-history [string] Same as ‘history’ argument for render.json.
X-Splash-har [string] Same as ‘har’ argument for render.json.
Note: Proxying of HTTPS requests is not supported.
Curl examples:
# Display json stats
curl -x localhost:8051 -H ’X-Splash-render: json’ \
http://www.domain.com
# Get the html page and screenshot
curl -x localhost:8051 \
-H "X-Splash-render: json" \
-H "X-Splash-html: 1" \
-H "X-Splash-png: 1" \
http://www.mywebsite.com
# Execute JS and return output
curl -x localhost:8051 \
-H ’X-Splash-render: json’ \
-H ’X-Splash-script: 1’ \
-H ’X-Splash-js-source: function test(x){ return x; } test("abc");’ \
http://www.domain.com
# Send POST request to site and save screenshot of results
curl -X POST -d ’{"key":"val"}’ -x localhost:8051 -o screenshot.png \
-H ’X-Splash-render: png’ \
http://www.domain.com
Splash proxy mode is enabled by default; it uses port 8051. To change the port use --proxy-portnum option:
1.2. Splash HTTP API 15Splash Documentation, Release 1.5
python -m splash.server --proxy-portnum=8888
To disable Splash proxy mode run splash server with --disable-proxy option:
python -m splash.server --disable-proxy
1.3 Splash Scripts Tutorial
Warning: Scripting support is an experimental feature for early adopters; API could change in future releases.
1.3.1 Intro
Splash can execute custom rendering scripts written in Lua programming language. This allows to use Splash as a
browser automation tool similar to PhantomJS.
To execute a script and get the result back send it to execute endpoint in a lua_source argument.
Note: Most likely you’ll be able to follow Splash scripting examples even without knowing Lua. Nevertheless, the
language worths learning - with Lua you can, for example, write Redis, Nginx, Apache, World of Warcraft scripts,
create mobile apps using Moai or Corona SDK or use state of the arts Deep Learning framework Torch7. It is easy
to get started and there are good online resources available like Learn Lua in 15 minutes tutorial and Programming in
Lua book.
Let’s start with a basic example:
function main(splash)
splash:go("http://example.com")
splash:wait(0.5)
local title = splash:evaljs("document.title")
return {title=title}
end
If we submit this script to execute endpoint in a lua_source argument, Splash will go to example.com website,
wait until it loads, then wait 0.5s more, then get page title (by evaluating a JavaScript snippet in page context), and
then return the result as a JSON encoded object.
Note: Splash UI provides an easy way to try scripts: there is a code editor for Lua and a button to submit a script to
execute. Visit http://127.0.0.1:8050/ (or whatever host/port Splash is listening to).
1.3.2 Entry Point: the “main” Function
The script must provide “main” function; this function is called by Splash. The result of this function is returned as an
HTTP response. Script could contain other helper functions and statements, but ‘main’ is required.
In the first example ‘main’ function returned a Lua table (an associative array similar to JavaScript Object or Python
dict). Such results are returned as JSON. This will return {"hello":"world!"} string as an HTTP response:
function main(splash)
return {hello="world!"}
end
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Script can also return a string:
function main(splash)
return ’hello’
end
Strings are returned as-is (unlike tables they are not encoded to JSON). Let’s check it with curl:
$ curl ’http://127.0.0.1:8050/execute?lua_source=function+main%28splash%29%0D%0A++return+%27hello%27%
hello
“main” function receives an object that allows to control the “browser tab”. All Splash features are exposed using this
object. By a convention, this argument is called “splash”, but you are not required to follow this convention:
function main(please)
please:go("http://example.com")
please:wait(0.5)
return "ok"
end
1.3.3 Where Are My Callbacks?
Here is a part of the first example:
splash:go("http://example.com")
splash:wait(0.5)
local title = splash:evaljs("document.title")
The code looks like a standard procedural code; there are no callbacks or fancy control flow structures. It doesn’t mean
Splash works in a synchronous way; under the hood it is still async. When you call splash.wait(0.5), Splash
switches from the script to other tasks, and comes back after 0.5s.
It is possible to use loops, conditional statements, functions as usual in Splash scripts; this enables a more straightfor-
ward code.
Let’s check an example PhantomJS script:
var users = ["PhantomJS", "ariyahidayat", /*...*/];
function followers(user, callback) {
var page = require(’webpage’).create();
page.open(’http://mobile.twitter.com/’ + user, function (status) {
if (status === ’fail’) {
console.log(user + ’: ?’);
} else {
var data = page.evaluate(function () {
return document.querySelector(’div.profile td.stat.stat-last div.statnum’).innerText;
});
console.log(user + ’: ’ + data);
}
page.close();
callback.apply();
});
}
function process() {
if (users.length > 0) {
var user = users[0];
users.splice(0, 1);
followers(user, process);
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} else {
phantom.exit();
}
}
process();
The code is arguably tricky: process function implements a loop by creating a chain of callbacks; followers
function doesn’t return a value (it would be more complex to implement) - the result is logged to the console instead.
A similar Splash script:
users = {’PhantomJS’, ’ariyahidayat’}
function followers(splash, user)
local ok, msg = splash:go(’http://mobile.twitter.com/’ .. user)
if not ok then
return "?"
end
return splash:evaljs([[
document.querySelector(’div.profile td.stat.stat-last div.statnum’).innerText;
]]);
end
function process(splash, users)
local result = {}
for idx, user in ipairs(users) do
result[user] = followers(splash, user)
end
return result
end
function main(splash)
local users = process(splash, users)
return {users=users}
end
Observations:
• some Lua knowledge is helpful to be productive in Splash Scripts: ipairs, [[multi-line strings]]
or string concatenation via .. could be unfamiliar;
• in Splash variant followers function can return a result (a number of twitter followers); also, it doesn’t need
a “callback” argument;
• instead of a page.open callback which receives “status” argument there is a “blocking” splash:go call which
returns “ok” flag;
• error handling is different: in case of an HTTP 4xx or 5xx error PhantomJS doesn’t return an error code to
page.open callback - example script will try to get the followers nevertheless because “status” won’t be
“fail”; in Splash this error will be detected and ”?” will be returned;
• process function can use a standard Lua for loop without a need to create a recursive callback chain;
• instead of console messages we’ve got a JSON HTTP API;
• apparently, PhantomJS allows to create multiple page objects and run several page.open requests in parallel
(?); Splash only provides a single “browser tab” to a script via its splash parameter of main function (but
you’re free to send multiple concurrent requests with Lua scripts to Splash).
There are great PhantomJS wrappers like CasperJS and NightmareJS which (among other things) bring a sync-looking
syntax to PhantomJS scripts by providing custom control flow mini-languages. However, they all have their own
18 Chapter 1. DocumentationSplash Documentation, Release 1.5
gotchas and edge cases (loops? moving code to helper functions? error handling?). Splash scripts are standard Lua
code.
Note: PhantomJS itself and its wrappers are great, they deserve lots of respect; please don’t take this writeup as
an attack on them. These tools are much more mature and feature complete than Splash. Splash tries to look at the
problem from a different angle, but for each unique Splash feature there are ten unique PhantomJS features.
1.3.4 Living Without Callbacks
Note: For the curious, Splash uses Lua coroutines under the hood.
Internally, “main” function is executed as a coroutine by Splash, and some of the splash:foo() methods use
coroutine.yield. See http://www.lua.org/pil/9.html for Lua coroutines tutorial.
In Splash scripts it is not explicit which calls are async and which calls are blocking. It is a common criticism of
coroutines/greenlets; check e.g. this article for a good description of the problem. However, we feel that in Splash
scripts negative effects are not quite there: scripts are meant to be small, shared state is minimized, and an API is
designed to execute a single command at time, so in most cases the control flow is linear.
If you want to be safe then think of all splash methods as of async; consider that after you call splash:foo()
a webpage being rendered can change. Often that’s the point of calling a method, e.g. splash:wait(time) or
splash:go(url) only make sense because webpage changes after calling them, but still - keep it in mind.
Currently async methods are splash:go, splash:wait, splash:wait_for_resume, splash:http_get and splash:set_content;
splash:autoload becomes async when an URL is passed. Most splash methods are currently not async, but thinking
of them as of async will allow your scripts to work if we ever change that.
1.3.5 Calling Splash Methods
Unlike many languages, in Lua methods are usually separated from an object using a colon :; to call “foo” method of
“splash” object use splash:foo() syntax. See http://www.lua.org/pil/16.html for more details.
There are two main ways to call Lua methods in Splash scripts: using positional and named arguments. To call a
method using positional arguments use parentheses splash:foo(val1, val2), to call it with named arguments
use curly braces: splash:foo{name1=val1, name2=val2}:
-- Examples of positional arguments:
splash:go("http://example.com")
splash:wait(0.5, false)
local title = splash:evaljs("document.title")
-- The same using keyword arguments:
splash:go{url="http://example.com"}
splash:wait{time=0.5, cancel_on_redirect=false}
local title = splash:evaljs{source="document.title"}
-- Mixed arguments example:
splash:wait{0.5, cancel_on_redirect=false}
For the convenience all splash methods are designed to support both styles of calling. But note that generally this
convention is not followed in Lua. There are no “real” named arguments in Lua, and most Lua functions (including
the ones from the standard library) choose to support only one style of calling. Check http://www.lua.org/pil/5.3.html
for more info.
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1.3.6 Error Handling
There are two ways to report errors in Lua: raise an exception and return an error flag. See
http://www.lua.org/pil/8.3.html.
Splash uses the following convention:
1. for developer errors (e.g. incorrect function arguments) exception is raised;
2. for errors outside developer control (e.g. a non-responding remote website) status flag is returned: functions
that can fail return ok, reason pairs which developer can either handle or ignore.
If main results in an unhandled exception then Splash returns HTTP 400 response with an error message.
It is possible to raise an exception manually using Lua error function:
error("A message to be returned in a HTTP 400 response")
To handle Lua exceptions (and prevent Splash from returning HTTP 400 response) use Lua pcall; see
http://www.lua.org/pil/8.4.html.
To convert “status flag” errors to exceptions Lua assert function can be used. For example, if you expect a website
to work and don’t want to handle errors manually, then assert allows to stop processing and return HTTP 400 if the
assumption is wrong:
local ok, msg = splash:go("http://example.com")
if not ok then
-- handle error somehow, e.g.
error(msg)
end
-- a shortcut for the code above: use assert
assert(splash:go("http://example.com"))
1.3.7 Sandbox
By default Splash scripts are executed in a restricted environment: not all standard Lua modules and functions are
available, Lua require is restricted, and there are resource limits (quite loose though).
To disable the sandbox start Splash with --disable-lua-sandbox option:
$ python -m splash.server --disable-lua-sandbox
1.3.8 Custom Lua Modules
Splash provides a way to use custom Lua modules (stored on server) from scripts passed via HTTP API. This allows
to
1. reuse code without sending it over network again and again;
2. use third-party Lua modules;
3. implement features which need unsafe code and expose them safely in a sandbox.
Note: To learn about Lua modules check e.g. http://lua-users.org/wiki/ModulesTutorial. Please prefer “the new
way” of writing modules because it plays better with a sandbox. A good Lua modules style guide can be found here:
http://hisham.hm/2014/01/02/how-to-write-lua-modules-in-a-post-module-world/
20 Chapter 1. DocumentationSplash Documentation, Release 1.5
Setting Up
To use custom Lua modules, do the following steps:
1. setup the path for Lua modules and add your modules there;
2. tell Splash which modules are enabled in a sandbox;
3. use Lua require function from a script to load a module.
To setup the path for Lua modules start Splash with --lua-package-path option. --lua-package-path
value should be a semicolon-separated list of places where Lua looks for modules. Each entry should have a ? in it
that’s replaced with the module name.
Example:
$ python -m splash.server --lua-package-path "/etc/splash/lua_modules/?.lua;/home/myuser/splash-modul
Note: If you use Splash installed using Docker see Folders Sharing for more info on how to setup paths.
Note: For the curious: --lua-package-path value is added to Lua package.path.
When you use a Lua sandbox (default) Lua require function is restricted when used in scripts: it only allows to load
modules from a whitelist. This whitelist is empty by default, i.e. by default you can require nothing. To make your
modules available for scripts start Splash with --lua-sandbox-allowed-modules option. It should contain a
semicolon-separated list of Lua module names allowed in a sandbox:
$ python -m splash.server --lua-sandbox-allowed-modules "foo;bar" --lua-package-path "/etc/splash/lua
After that it becomes possible to load these modules from Lua scripts using require:
local foo = require("foo")
function main(splash)
return {result=foo.myfunc()}
end
Writing Modules
A basic module could look like the following:
-- mymodule.lua
local mymodule = {}
function mymodule.hello(name)
return "Hello, " .. name
end
return mymodule
Usage in a script:
local mymodule = require("mymodule")
function main(splash)
return mymodule.hello("world!")
end
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Many real-world modules will likely want to use splash object. There are several ways to write such modules. The
simplest way is to use functions that accept splash as an argument:
-- utils.lua
local utils = {}
-- wait until ‘condition‘ function returns true
function utils.wait_for(splash, condition)
while not condition() do
splash:wait(0.05)
end
end
return utils
Usage:
local utils = require("utils")
function main(splash)
splash:go(splash.args.url)
-- wait until element is loaded
utils.wait_for(splash, function()
return splash:evaljs("document.querySelector(’h1’) != null")
end)
return splash:html()
end
Another way to write such module is to add a method to splash object. This can be done by adding a method to its
Splash class - the approach is called “open classes” in Ruby or “monkey-patching” in Python.
-- wait_for.lua
-- Sandbox is not enforced in custom modules, so we can import
-- internal Splash class and change it - add a method.
local Splash = require("splash")
function Splash:wait_for(condition)
while not condition() do
self:wait(0.05)
end
end
-- no need to return anything
Usage:
require("wait_for")
function main(splash)
splash:go(splash.args.url)
-- wait until element is loaded
splash:wait_for(function()
return splash:evaljs("document.querySelector(’h1’) != null")
end)
return splash:html()
22 Chapter 1. DocumentationSplash Documentation, Release 1.5
end
Which style to prefer is up to the developer. Functions are more explicit and composable, monkey patching enables a
more compact code. Either way, require is explicit.
As seen in a previous example, sandbox restrictions for standard Lua modules and functions are not applied in
custom Lua modules, i.e. you can use all the Lua powers. This makes it possible to import third-party Lua modules
and implement advanced features, but requires developer to be careful. For example, let’s use os module:
-- evil.lua
local os = require("os")
local evil = {}
function evil.sleep()
-- Don’t do this! It blocks the event loop and has a startup cost.
-- splash:wait is there for a reason.
os.execute("sleep 2")
end
function evil.touch(filename)
-- another bad idea
os.execute("touch " .. filename)
end
-- todo: rm -rf /
return evil
1.3.9 Timeouts
By default Splash aborts script execution after the timeout (30s by default). To override the timeout value use ‘timeout’
argument of the /execute endpoint.
Note that the maximum allowed timeout value is limited by the maximum timeout setting, which is by default 60
seconds. In other words, by default you can’t pass ?timeout=300 to run a long script - an error will be returned. It
is quite typical for scripts to work longer than 60s, so if you use Splash scripts it is recommended to explicitly set the
maximum possible timeout by starting Splash with --max-timeout command line option:
$ python -m splash.server --max-timeout 3600
Note: See Passing Custom Options if you use Docker to run Splash.
1.4 Splash Scripts Reference
Warning: Scripting support is an experimental feature for early adopters; API could change in future releases.
splash object is passed to main function; via this object a script can control the browser. Think of it as of an API
to a single browser tab.
1.4. Splash Scripts Reference 23Splash Documentation, Release 1.5
1.4.1 splash:go
Go to an URL. This is similar to entering an URL in a browser address bar, pressing Enter and waiting until page
loads.
Signature: ok, reason = splash:go{url, baseurl=nil, headers=nil}
Parameters:
• url - URL to load;
• baseurl - base URL to use, optional. When baseurl argument is passed the page is still loaded from url, but
it is rendered as if it was loaded from baseurl: relative resource paths will be relative to baseurl, and the
browser will think baseurl is in address bar;
• headers - a Lua table with HTTP headers to add/replace in the initial request.
Returns: ok, reason pair. If ok is nil then error happened during page load; reason provides an information
about error type.
Three types of errors are reported (ok can be nil in 3 cases):
1. There is nothing to render. This can happen if a host doesn’t exist, server dropped connection, etc. In this case
reason is "error".
2. Server returned a response with 4xx or 5xx HTTP status code. reason is "http" in this case, i.e.
for HTTP 404 Not Found reason is "http404".
3. Navigation is locked (see splash:lock_navigation); reason is "navigation_locked".
Error handling example:
local ok, reason = splash:go("http://example.com")
if not ok then
if reason:sub(0,4) == ’http’ then
-- handle HTTP errors
else
-- handle other errors
end
end
-- process the page
-- assert can be used as a shortcut for error handling
assert(splash:go("http://example.com"))
Errors (ok==nil) are only reported when “main” webpage request failed. If a request to a related resource failed then
no error is reported by splash:go. To detect and handle such errors (e.g. broken image/js/css links, ajax requests
failed to load) use splash:har.
splash:go follows all HTTP redirects before returning the result, but it doesn’t follow HTML redirects or redirects initiated by JavaScript code. To give the webpage time
to follow those redirects use splash:wait.
headers argument allows to add or replace default HTTP headers for the initial request. To set custom headers for
all further requests (including requests to related resources) use splash:set_custom_headers.
Custom headers example:
local ok, reason = splash:go{"http://example.com", headers={
["Custom-Header"] = "Header Value",
}})
24 Chapter 1. DocumentationSplash Documentation, Release 1.5
User-Agent header is special: once used, it is kept for further requests. This is an implementation detail and it could
change in future releases; to set User-Agent header it is recommended to use splash:set_user_agent method.
1.4.2 splash:wait
Wait for time seconds. When script is waiting WebKit continues processing the webpage.
Signature: ok, reason = splash:wait{time, cancel_on_redirect=false,
cancel_on_error=true}
Parameters:
• time - time to wait, in seconds;
• cancel_on_redirect - if true (not a default) and a redirect happened while waiting, then splash:wait stops
earlier and returns nil, "redirect". Redirect could be initiated by HTML tags or by JavaScript code.
• cancel_on_error - if true (default) and an error which prevents page from being rendered happened while waiting
(e.g. an internal WebKit error or a network error like a redirect to a non-resolvable host) then splash:wait
stops earlier and returns nil, "error".
Returns: ok, reason pair. If ok is nil then the timer was stopped prematurely, and reason contains a string
with a reason. Possible reasons are "error" and "redirect".
Usage example:
-- go to example.com, wait 0.5s, return rendered html, ignore all errors.
function main(splash)
splash:go("http://example.com")
splash:wait(0.5)
return {html=splash:html()}
end
By default wait timer continues to tick when redirect happens. cancel_on_redirect option can be used to restart
the timer after each redirect. For example, here is a function that waits for a given time after each page load in case of
redirects:
function wait_restarting_on_redirects(splash, time, max_redirects)
local redirects_remaining = max_redirects
while redirects_remaining do
local ok, reason = self:wait{time=time, cancel_on_redirect=true}
if reason ~= ’redirect’ then
return ok, reason
end
redirects_remaining = redirects_remaining - 1
end
return nil, "too_many_redirects"
end
1.4.3 splash:jsfunc
Convert JavaScript function to a Lua callable.
Signature: lua_func = splash:jsfunc(func)
Parameters:
• func - a string which defines a JavaScript function.
1.4. Splash Scripts Reference 25Splash Documentation, Release 1.5
Returns: a function that can be called from Lua to execute JavaScript code in page context.
Example:
function main(splash)
local get_div_count = splash:jsfunc([[
function (){
var body = document.body;
var divs = body.getElementsByTagName(’div’);
return divs.length;
}
]])
splash:go(splash.args.url)
return get_div_count()
end
Note how Lua [[ ]] string syntax is helpful here.
JavaScript functions may accept arguments:
local vec_len = splash:jsfunc([[
function(x, y) {
return Math.sqrt(x*x + y*y)
}
]])
return {res=vec_len(5, 4)}
Global JavaScript functions can be wrapped directly:
local pow = splash:jsfunc("Math.pow")
local twenty_five = pow(5, 2) -- 5^2 is 25
local thousand = pow(10, 3) -- 10^3 is 1000
Lua strings, numbers, booleans and tables can be passed as arguments; they are converted to JS
strings/numbers/booleans/objects. Currently it is not possible to pass other Lua objects. For example, it is not possible
to pass a wrapped JavaScript function or a regular Lua function as an argument to another wrapped JavaScript function.
Lua → JavaScript conversion rules:
Lua JavaScript
string string
number number
boolean boolean
table Object
nil undefined
Function result is converted from JavaScript to Lua data type. Only simple JS objects are supported. For example,
returning a function or a JQuery selector from a wrapped function won’t work. JavaScript → Lua conversion rules:
26 Chapter 1. DocumentationSplash Documentation, Release 1.5
JavaScript Lua
string string
number number
boolean boolean
Object table
Array table
undefined nil
null "" (an empty string)
Date string: date’s ISO8601 representation, e.g. 1958-05-21T10:12:00Z
RegExp table {_jstype=’RegExp’, caseSensitive=true/false,
pattern=’my-regexp’}
function an empty table {} (don’t rely on it)
Function arguments and return values are passed by value. For example, if you modify an argument from inside a
JavaScript function then the caller Lua code won’t see the changes, and if you return a global JS object and modify it
in Lua then object won’t be changed in webpage context.
Note: The rule of thumb: if an argument or a return value can be serialized via JSON, then it is fine.
If a JavaScript function throws an error, it is re-throwed as a Lua error. To handle errors it is better to use JavaScript
try/catch because some of the information about the error can be lost in JavaScript → Lua conversion.
See also: splash:runjs, splash:evaljs, splash:wait_for_resume, splash:autoload.
1.4.4 splash:evaljs
Execute a JavaScript snippet in page context and return the result of the last statement.
Signature: result = splash:evaljs(snippet)
Parameters:
• snippet - a string with JavaScript source code to execute.
Returns: the result of the last statement in snippet, converted from JavaScript to Lua data types. In case of syntax
errors or JavaScript exceptions an error is raised.
JavaScript → Lua conversion rules are the same as for splash:jsfunc.
splash:evaljs is useful for evaluation of short JavaScript snippets without defining a wrapper function. Example:
local title = splash:evaljs("document.title")
Don’t use splash:evaljs when the result is not needed - it is inefficient and could lead to problems; use splash:runjs
instead. For example, the following innocent-looking code (using jQuery) may fail:
splash:evaljs("$(console.log(’foo’));")
A gotcha is that to allow chaining jQuery $ function returns a huge object, splash:evaljs tries to serialize it and convert
to Lua. It is a waste of resources, and it could trigger internal protection measures; splash:runjs doesn’t have this
problem.
If the code you’re evaluating needs arguments it is better to use splash:jsfunc instead of splash:evaljs and string
formatting. Compare:
function main(splash)
local font_size = splash:jsfunc([[
function(sel) {
1.4. Splash Scripts Reference 27You can also read
